Dodge ESX3

The Green Brigade

May 2001 By AARON ROBINSON

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The real story of DaimlerChrysler's PNGV entry can be summed up in one word: plastics. Although the Metalcrafters shop in California built the concept car pictured here from hand-formed aluminum to save tooling costs, engineers designed the unitized body shell to come together from just 12 plastic moldings like a SnapTite model of the Charlie's Angels van. Aluminum tubes bonded internally to the plastic, what engineers have dubbed the "sparse frame," would keep the polymer pieces from wobbling. Some cavities would be filled with thermoset polyurethane foam braced by steel reinforcements.

DaimlerChrysler honchos have whiled away many an hour daydreaming about such cars assembled from a few large pieces of injection-molded thermoplastic. The benefits: cheap tooling, the potential to mold in color so there is no expensive paint shop, and a low resulting weight. A plastic car such as the 2250-pound ESX3 could pop out of the molding 46 percent lighter than an equivalent steel job and 15 percent cheaper, says DaimlerChrysler.

The ESX3 in mass production would cost only a claimed $7500 more than today's Dodge Intrepid, due mainly to the extra cost associated with the hybrid powertrain. And DaimlerChrysler claims 80 percent of the car could be recycled, perhaps into an S-class cup holder.

Detroit Diesel took a break from building 3300-hp tugboat engines to create the ESX3's 1.5-liter, three-cylinder direct-injection turbo-diesel. The 74-hp pipsqueak features an aluminum block and head, weighs in at just 249 pounds, and redlines at a lazy 4200 rpm. Even with its variable-geometry turbocharger, it wouldn't pull the cheese off a cold pizza without help from the 20-hp air-cooled Delphi flywheel-type electric motor sandwiched between the crankshaft and the six-speed manual transaxle. The gearbox, which is shifted automatically by the computer, accepts power via twin clutches that work in tandem to smooth over the big torque holes inherent in clutched transmissions.

We took a brief run around a nearby park, and the fancy transmission acquitted itself best during hard acceleration, when shifts were their smoothest. The ESX3 feels more ponderous than one would expect for a car weighing 10 pounds less than a Toyota MR2 Spyder, in part because the ultra-hard prototype Goodyear Eagle tires provide low rolling resistance but offer little bite in the corners. The regenerative brakes feel almost normal, unlike some hybrids whose nonlinear binders grab too hard too early. Pressure in the electronically managed turbo seems to build quickly and with no discernible lag. DaimlerChrysler claims a 0-to-60-mph time of 11.0 seconds, a number we were not able to validate but have no reason to doubt.

As in the Honda Insight, the motor never operates solo. It provides motive assistance during acceleration, generates power for the battery pack, and restarts the engine after idle shutdowns. Regenerative braking helps keep the 106-pound, 165-volt, 1.0-kilowatt-hour lithium-ion battery pack topped off.

Plastic isn't a panacea. Problems remain, including the fact that you can have any color as long as it is flat. And do you remember what happened when your Charlie's Angels van rolled off the table? Plastic doesn't deform predictably like metal. The 2001 Jeep Wrangler's one-piece plastic hardtop proves DaimlerChrysler is still interested in injection-molding large pieces for mass production, but it isn't clear where this initiative will go now that English is the second language in Auburn Hills.